Ozone (O.sub.3) is a triatomic allotrope of oxygen in which the ozone molecule consists of three oxygen atoms in contrast to the two oxygen atoms which comprise the typical oxygen molecule (O.sub.2). Ozone can be generated by passing air or oxygen through a high intensity electric field. Some of the oxygen molecules will be energized and will split into two separate atoms. These individual oxygen atoms will then form weak bonds with other oxygen molecules. The ozone molecule is oxygen in a highly reactive form, which has a tendency to give up its extra oxygen atom and gain electrons. This molecular structure gives ozone its high oxidizing power which allows ozone to react rapidly with a large variety of compounds.
Although ozone has been primarily employed in disinfection of culinary water and municipal waste water treatment, it can perform other functions such as color reduction, odor and taste removal, and oxidation of inorganic and organic compounds in water.
Ozone acts as a positively charged molecule that is electron deficient. Organic and hydrocarbon stains such as greases, fats, and oils have centers of high electron density and carry a negative charge. When ozone is introduced into a washing machine, it is attracted to these molecules and subsequently reacts chemically with the soil in an oxidation process. The kinetics of the reaction between soil and ozone is very high; thus, the reaction between these two substances is extremely fast. Ozone will begin to react within a fraction of a second after contact. In the process, ozone will give up its third oxygen atom, which will chemically bond with the soil molecule. An oxygen atom is highly electronegative and when added to a soil molecule, the electronegative charge will cause the chemical double bond of the molecule to polarize (reverse charge). Polarization will cause a large soil molecule to fragment into several smaller molecules. The strength of attachment between soil and a textile is largely a function of the size of the soil molecule. Smaller soil molecules will be more easily removed from the textile. The size of the molecule also has a direct effect on the solubility of the soil whereby a reduction in molecular size of the soil will greatly increase the amount of soil that is dissolved in the wash liquor.
Surfactants and alkalis are used in most laundry detergents. Their main purpose is to suspend soil by bonding with the soil molecules to prevent redeposition of the soil. Additionally, surfactants play a key role in loosening of the soil. Some soils can be removed from the textile surface by mechanical action and water alone, but the majority cannot. Thus, a major part of the role of the surfactant is to loosen and dissolve soil from the textile. However, this task can be facilitated by ozone. A primary purpose of ozone in laundry processing is to remove the soil from the textile through polarization. A secondary purpose is to oxidize the soil molecules, making it more soluble and allowing for faster precipitation. Ozone is in a highly reactive gaseous form in laundry processing, allowing it to react with and remove soil at a greatly increased rate which accounts for a substantial reduction in processing time.
Alkalis are used for controlling the pH and active alkalinity of the wash water. Alkalis bond with cations, such as calcium and magnesium, allowing surfactants to react with soils more effectively. Alkalis can sequester the hardness in water and can prevent calcium and magnesium from forming insoluble soaps. Alkalis have superior soil suspending properties which contribute to the function of surfactants and ozone. Thus, when using ozone as a wash chemical, it is only necessary to use a small mount of alkali on heavy industrial soil and in the bleach cycle for pH control.
Solvents are used to hold other substances, such as surfactants and alkalis, in solution and dissolve soils found on the textile to be cleaned.
The use of ozone in the laundry process reduces or eliminates the need for other laundry chemicals and finishing products such as antichlor, "sour", bactericides, and mildewcides. Antichlor is used to neutralize any residual chlorine bleach. Ozone oxidizes chlorine bleach and completely neutralizes it. For this reason, ozone is not used in a chlorine bleach cycle. However, since ozone has bleaching capability, the need for chlorine bleach is reduced and, consequently, the need for antichlor is likewise reduced. Sour is used to neutralize the effects of alkali on the pH of the wash solution. Since the use of ozone greatly reduces the need for alkali, the need for sour is also reduced or altogether eliminated.
Ozone is the strongest oxidant commercially available for the treatment of water. Due to ozone's high oxidation potential, the duration of the wash cycle can be reduced relative to those cycles using chlorine as an oxidant, while attaining the same or higher oxidative capabilities. Wash temperatures and alkalinity can also be reduced. These contribute to increased textile life by decreasing stress on the fabric through limited mechanical action, more neutral pH's and lower temperatures. It also enhances washroom throughput.
It would be an improvement in the art to have a relatively economical, reliable cold water washing formula and method of washing and deodorizing textiles such as garments or linens.